Greyscale, the thing that we saw Jorah Mormont suffering with is not common in Essos. We all know Shereen Baratheon was affected by it and got cured and their are few cases of Greyscale in Westeros. But nobody expects this disease to be found North of the Wall.
But it turns out they have it there as well. In the 1st Episode of Game of Thrones Season 5, Gilly tells Shereen and Sam the story of how here 2 sisters got affected by Greyscale and how her father/husband dragged them into the woods with ropes.
And we all know what happens when he left someone in the woods. So will the Stone Men or Stone Women join the Night King and battle our heroes?
I think they might because so far the story of Jorah Mormont and Greyscale has been pretty boring and pointless. But there is nothing boring in Game of Thrones.
So my theory is Sam found something more about Greyscale while treating Jorah and he might have said the same to him. So in the war to come Jorah will fight the Stone Men with that knowledge.
Now all we have to do is wait for the Long Night now and watch what happens.
